In 2006 the Congressional Research Service (CRS) compiled a report on the use of earmarks in thirteen Appropriation Acts from 1994 through 2005 in which they noted that there was "not a single definition of the term earmark accepted by all practitioners and observers of the appropriations process, nor [was] there a standard earmark practice across all appropriation bills."[5]:2 It was noted at that time, that while the CRS did not summarize earmarks that they came in two varieties: hard earmarks, or "hardmarks", found in legislation, and soft earmarks, or "softmarks", found in the text of congressional committee reports. Hard earmarks are legally binding, whereas soft earmarks are not but are customarily acted upon as if they were.[6][5] The CRS did not aggregate the "varying definitions" as the result would be invalid.[5]:3[7]:4

"Provisions associated with legislation (appropriations or general legislation) that specify certain congressional spending priorities or in revenue bills that apply to a very limited number of individuals or entities. Earmarks may appear in either the legislative text or report language (committee reports accompanying reported bills and joint explanatory statement accompanying a conference report)."

— Sandy Streeter, Government and Finance Division, March 6, 2006 CRS

According to the federal Office of Management and Budget the term earmark referred to,[9]

"funds provided by the Congress for projects, programs, or grants where the purported congressional direction (whether in statutory text, report language, or other communication) circumvents otherwise applicable merit-based or competitive allocation processes, or specifies the location or recipient, or otherwise curtails the ability of the executive branch to manage its statutory and constitutional responsibilities pertaining to the funds allocation process. Earmarks are funds provided by Congress for projects or programs that curtail the ability of the Executive Branch to manage critical aspects of the funds allocation process."

— Office of Management and Budget. Last updated 2011

In 2015, for the purpose of clause 9(e) of rule XXI restricting certain bills in the Rules of the House of Representatives for the 114th Congress, Congressional earmarks were defined as,[1]:36

"a provision or report language included primarily at the request of a Member, Delegate, Resident Commissioner, or Senator providing, authorizing or recommending a specific amount of discretionary budget authority, credit authority, or other spending authority for a contract, loan, loan guarantee, grant, loan authority, or other expenditure with or to an entity, or targeted to a specific State, locality or Congressional district, other than through a statutory or administrative formula-driven or competitive award process."

— Clerk of the House of Representatives January 15, 2015

The House Rules impose disclosure requirements for earmarks, while a standing rule of the Republican Conference has, since the 114th Congress, imposed an "earmark moratorium".[7]:1

Typically, a legislator seeks to insert earmarks that direct a specified amount of money to a particular organization or project in their home state or district.

The earmarking process provided Congress with the power to earmark discretionary funds it appropriates to be spent on specific named projects. The earmarking process was a regular part of the process of allocating funds within the Federal government. For many years they were a core aspect of legislative policymaking and distributive politics - an essential political instrument whereby "political coalitions were forged through compromise in order to pass or reject key legislation. As congressional earmarks came into disfavor and eventually were prohibited, the ban "contributed to legislative gridlock and increased the difficulty of winning enactment of tax and immigration reform."[17][18][19]

Earmarking differs from the broader appropriations process in which Congress grants a yearly lump sum of money to a federal agency. These monies are allocated by the agency according to its legal authority and internal budgeting process. With an earmark, Congress directs a specified amount of money from an agency's budget to be spent on a particular project. In the past members of Congress did not have to identify themselves or the project.

The process of earmarking was substantially reformed since the "110th United States Congress between January 3, 2007, and January 3, 2009. Since 2009, members of Congress had to post all their earmark requests online along with a signed letter certifying that they and their immediate families had no direct financial interest in the earmark.[20]

In March 2010, the House Appropriations Committee implemented rules to ban earmarks to for-profit corporations. According to the "New York Times, approximately 1,000 such earmarks were authorized in the previous year, worth $1.7 billion.[21]

In November 2010, the GOP promised to ban earmarks.[22] House Speaker "John Boehner declared that earmarks were "the pet projects prized by lawmakers that had become synonymous with pork-barrel spending and corruption."[23][24]

President Obama promised during his State of the Union address in January 2011 to veto any bill that contained earmarks. In February 2011, Congress "imposed a temporary ban on earmarks, money for projects that individual lawmakers slip into major Congressional budget bills to cater to local demands."[18]

Finally, earmarks constituted less than 1% of the 2010 federal budget, down from about 1.1% in 2006.[27]

In December 2015, "Citizens Against Government Waste (CAGW), claimed in their 2016 Congressional Pig Book,[28] that all the FY2016 earmarks were contained in the December 2016 omnibus 2000-page "Consolidated Appropriations Act, 2016 which authorized $1.15 trillion in appropriations.[29] The CAGW argued that "Throwing all earmarks into one large bill makes it more difficult to identify and eliminate earmarks than if Congress adhered to regular order and considered the 12 appropriations bills individually."

"Paul Ryan announced that the Republican party is considering calling for an end to the ban earmarks. Supporters of ending the ban are now calling earmarks "congressionally directed spending."[23]

Members of Congress can influence priorities and policy-making that promote projects that are important to their constituents by accessing discretionary DOT spending, through regular formula-based funding mechanisms and increased interaction with both transportation official as the federal and state levels.[6]:9

In January 2017, a report by the CRS described how, prior to the earmarks ban in 2011, Members of Congress had used earmarks to ensure that local congressional representatives, not the "Department of Transportation and its Agencies Administration, set priority discretionary transportation spending.[6]:9

Earmarks have often been treated as being synonymous with ""pork barrel" legislation.[31] Despite considerable overlap,[32] the two are not the same: what constitutes an earmark is an objective determination, while what is "pork-barrel" spending is subjective.[33] One legislator's "pork" is another's vital project.[34][35]

Scott Frisch and Sean Kelly point out that directing money to particular purposes is a core constitutional function of Congress. If Congress does not make a specific allocation, the task falls to the executive branch. There is no guarantee that the allocation made by executive agencies will be superior to that of Congress. Presidents and executive officials can use the allocation of spending to reward friends and punish enemies. [36]["page needed]

There are also those who opine that "earmarks are good" because they are more democratic and less bureaucratic than traditional appropriation spending, which generally is not tailored to specific projects.[37]

In 2010, National Treasury Republic of South Africa explored earmarking[39] , along with recycling and tax shifting, as ways of using carbon tax revenues. While the Treasury did "not support full earmarking of revenues generated from environmental taxes" they were considering "partial 'on-budget' earmarking of some revenue. At that time concerns were raised that special interest groups could constrain government and control public resources through earmarking.[39]:8